Facile synthesis, characterization, and ab‐initio DFT simulations of energy efficient NN′ dialkyl 1,4 benzene dicarboxamide monomers recovered from PET bottle waste

Abstract

Aminolytic chemical recycling is performed for obtaining NN′ diethyl 1,4 benzene dicarboxamide, NN′ dibutyl 1,4 benzene dicarboxamide, and NN′ dihexyl 1,4 benzene dicarboxamide from Polyethylene terephthalate bottle waste. The compounds were characterized through Fourier transform Infrared spectroscopy, Raman spectroscopy, UV–Visible spectroscopy, 1H NMR, 13C NMR, mass spectrometry, and elemental analysis. Thermal properties were also analyzed with the help of thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Density Functional Theory (DFT) study has been performed at GGA‐BLYP (Becke's and Lee–Yang–Parr) functional using SZ basis set to investigate the vibrational frequencies and physical parameters. Experimental vibrational frequencies were found in good accord with the experimental values. Calorific values of the products have been determined using bomb calorimeter as per standard ASTM D240. The values have been correlated with increment of methylene units from NN′ diethyl BdCA to NN′ dihexyl BdCA using standard molar enthalpies of carbon and hydrogen. SEM and EDX analysis of the char residues after combustion has also been carried out to insight the effect of N‐alkyl chain length on calorific values. The calorific values of the recovered compounds are comparable to commercial solid fuels and the compounds may find potential applications in aerospace industry.

Recent Trends of Recycling and Upcycling of Polymers and Composites: A Comprehensive Review

“…It is known that the more substituted structure is the more reactive, and thus, ammonia has not been investigated as much as amines have [252]. The product obtained by ammonolysis is terephthalic acid diamide (TPADA), which can be used as an additive to PVC [253]; otherwise, through via pyrolytic dehydration, we can obtain aromatic nitrile compounds that can be hydrogenated to aminomethyl derivatives, i.e., p-xylene, diamine, 4-(aminomethyl) benzoic acid, 1,4 benzene dicarboxamide, etc., that are valuable chemicals and can be used for many applications such as monomers for polyamide synthesis [254,255].…”

Opportunities in Closed-Loop Molecular Recycling of End-of-Life Polyurethane

“…Computational techniques have been used to study glycolysis, acidolysis, hydrolysis, and aminolysis but not in the context of PU reactions. Unlike many of the systems studied, PU is a large polymeric molecule that can exhibit hydrogen bonding both between the polymer chains (intramolecular hydrogen bonding) and with solvent or reagent molecules (intermolecular hydrogen bonding). − There are some studies, however, that addressed other systems with similar characteristics.…”

Research and progress of chemical depolymerization of waste PET and high-value application of its depolymerization products

“…Teotio et al 30 used ethylamine, n -butylamine and n -hexylamine as ammonolysis reagents to chemically recover N , N -dialkyl-1,4-benzenedicarboxamide, a product with a calorific value equivalent to coal, from waste PET bottles through ammonolysis without catalyst. The calorific value of this compound is theoretically comparable to that of solid fuel, and it can be used as a new type of propellant in the missile and aerospace industries in the future.…”